4.0 sohc spark plug change

[perth]

Happy new year to all,ive just spent to many hours changing the plugs and leads on my ex,one plug the passengers front was just painful(right hand drive model)eventually all done and she started first pop and drives a lot more willingly but there is a slight miss at idle that wasnt there before,at revs its not noticeable,the old plugs were in a long time could have been for the life of the car(1998) the electrode was worn and the gap was very wide,im sure the leads are connecting properly with the spark plug cap.Even though the old plugs were so worn it still idled as smooth as any car ive owned,now the new plugs are in its definetly a better drive but doesnt idle as smooth,any ideas or is this just a ex "normal" idle problem cheers from Oz.

 

[gijoecam]

Did you replace the wires as well? If not, I'd start there.

 

[perth]

Yes new leads ,bought them from the US,Motorcraft ,supposedly to fit a 4.0 sohc but one lead was to short and had to use one of the old ones,its driving really well but at idle every now and again it just has a small stutter,could i check the leads by unplugging them one at a time ?or would it idle rough just running on 5 cylinders,is there any way of checking leads simply?cheers.

 

[bluestream1]

Try here to plug wire test procedure:

http://www.ehow.com/how_2296047_test-spark-plug-wire-car.html